This application is a continuation of PCT/US93/06074.
This invention relates generally to copolycarbonates; their method of preparation; their use in preparing improved polymeric bodies; and the improved polymeric bodies. More specifically, the invention concerns novel 4,4'-thiodiphenol (TDP) copolycarbonates having properties that make them particularly suitable for preparing certain types of multilayered polymeric bodies.
U.S. Pat. Nos. 5,122,905 and 5,122,906 teach the use of polycarbonates in preparing highly reflective multilayered polymeric bodies. The only polycarbonate it specifically discloses in its Examples is a homopolycarbonate of bisphenol A (Calibre 300-22, trademark of The Dow Chemical Company). We concluded that it would be desirable to provide materials with improvements in glass transition temperature (Tg), refractive index (RI), and limiting oxygen index (LOI). Such materials would significantly expand the application areas for the multilayered polymeric bodies.
In addition, several recent published patent applications teach the use of (previously known) copolycarbonates of 4,4'-thiodiphenol (TDP) and bisphenol A (BA) as the high refractive index (RI) component of a multilayered polymeric reflective body.